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Environment Effects (environment + effects)
Selected AbstractsHERITABILITY OF AND EARLY ENVIRONMENT EFFECTS ON VARIATION IN MATING PREFERENCESEVOLUTION, Issue 4 2010Holger Schielzeth Many species show substantial between-individual variation in mating preferences, but studying the causes of such variation remains a challenge. For example, the relative importance of heritable variation versus shared early environment effects (like sexual imprinting) on mating preferences has never been quantified in a population of animals. Here, we estimate the heritability of and early rearing effects on mate choice decisions in zebra finches based on the similarity of choices between pairs of genetic sisters raised apart and pairs of unrelated foster sisters. We found a low and nonsignificant heritability of preferences and no significant shared early rearing effects. A literature review shows that a low heritability of preferences is rather typical, whereas empirical tests for the relevance of sexual imprinting within populations are currently limited to very few studies. Although effects on preference functions (i.e., which male to prefer) were weak, we found strong individual consistency in choice behavior and part of this variation was heritable. It seems likely that variation in choice behavior (choosiness, responsiveness, sampling behavior) would produce patterns of nonrandom mating and this might be the more important source of between-individual differences in mating patterns. [source] Gene,environment interactions and alcohol use and dependence: current status and future challengesADDICTION, Issue 6 2009Carmen S. Van Der Zwaluw ABSTRACT Aim To discuss the current status of gene,environment interaction research with regard to alcohol use and dependence. Further, we highlight the difficulties concerning gene,environment studies. Methods Overview of the current evidence for gene,environment interactions in alcohol outcomes, and of the associated challenges in gene,environment studies. Results Attention to the causative roles of gene,environment interactions in alcohol use and dependence is increasing. Studies with twin designs are beginning to examine gene-shared environment effects, and animal studies have investigated gene,environment interaction effects on alcohol intake in primates. Thirteen studies incorporated gene,environment interactions in examining alcohol use or dependence in humans. These studies held a variety of candidate genes and environmental risk factors and their heterogeneity made it impossible to draw firm general conclusions. Conclusions Challenges for future gene,environment studies are abundant, and consist of, for example, the development of clear theoretical assumptions about neurobiological mechanisms and the recruitment of large longitudinal samples that already start in childhood. Replication is essential to prevent an overload of false-positive results. Despite the difficulties, it is crucial to include gene,environment interactions in future studies in order to unravel the aetiological factors of human alcohol outcomes. [source] Age,environment model for breast cancerENVIRONMETRICS, Issue 3 2004Nobutane Hanayama Abstract In the field of breast cancer study, it has become accepted that crucial exposures to environmental risks might have occurred years before a malignant tumor is evident in human breasts, while age factors such as ages at menstruation have been known as risks for the disease already. To project trends in two such kinds of risks for the disease, the concept of environment effects is introduced for (age, period)-specific breast cancer mortality rates. Also, a new model, named the age,environment (AE) model, which assumes that the logarithm of the expected rate is a linear function of environment effects and age effects, is proposed. It is shown that, although environment effects have different meanings from period effects or cohort effects, in the age,period,cohort (APC) model, the range space of the design matrix for the AE model is included in that for APC model. It is seen, however, that the AE model provides a better fit to the data for females in Japan and the four Nordic countries than does the APC model in terms of AIC. From the results of ML estimation of the parameters in the AE model based on the data obtained in Japan, we see high levels of environment effects associated with the Sino,Japanese war, World War II and the environmental pollution due to the economy in the recovery period from the defeat. Besides, from those based on the data obtained in the four Nordic countries, we see high levels of environment effects associated with the environment becoming worse after the year of Helsinki Olympics and low levels of them associated with the period including the year of ,Miracle of the Winter War' in Finland. Copyright © 2004 John Wiley & Sons, Ltd. [source] Bayesian hierarchical models in ecological studies of health,environment effectsENVIRONMETRICS, Issue 2 2003Sylvia Richardson Abstract We describe Bayesian hierarchical models and illustrate their use in epidemiological studies of the effects of environment on health. The framework of Bayesian hierarchical models refers to a generic model building strategy in which unobserved quantities (e.g. statistical parameters, missing or mismeasured data, random effects, etc.) are organized into a small number of discrete levels with logically distinct and scientifically interpretable functions, and probabilistic relationships between them that capture inherent features of the data. It has proved to be successful for analysing many types of complex epidemiological and biomedical data. The general applicability of Bayesian hierarchical models has been enhanced by advances in computational algorithms, notably those belonging to the family of stochastic algorithms based on Markov chain Monte Carlo techniques. In this article, we review different types of design commonly used in studies of environment and health, give details on how to incorporate the hierarchical structure into the different components of the model (baseline risk, exposure) and discuss the model specification at the different levels of the hierarchy with particular attention to the problem of aggregation (ecological) bias. Copyright © 2003 John Wiley & Sons, Ltd. [source] HERITABILITY OF AND EARLY ENVIRONMENT EFFECTS ON VARIATION IN MATING PREFERENCESEVOLUTION, Issue 4 2010Holger Schielzeth Many species show substantial between-individual variation in mating preferences, but studying the causes of such variation remains a challenge. For example, the relative importance of heritable variation versus shared early environment effects (like sexual imprinting) on mating preferences has never been quantified in a population of animals. Here, we estimate the heritability of and early rearing effects on mate choice decisions in zebra finches based on the similarity of choices between pairs of genetic sisters raised apart and pairs of unrelated foster sisters. We found a low and nonsignificant heritability of preferences and no significant shared early rearing effects. A literature review shows that a low heritability of preferences is rather typical, whereas empirical tests for the relevance of sexual imprinting within populations are currently limited to very few studies. Although effects on preference functions (i.e., which male to prefer) were weak, we found strong individual consistency in choice behavior and part of this variation was heritable. It seems likely that variation in choice behavior (choosiness, responsiveness, sampling behavior) would produce patterns of nonrandom mating and this might be the more important source of between-individual differences in mating patterns. [source] Early maternal, genetic and environmental components of antioxidant protection, morphology and immunity of yellow-legged gull (Larus michahellis) chicksJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 5 2006D. RUBOLINI Abstract Maternal effects mediated by egg quality are important sources of offspring phenotypic variation and can influence the course of evolutionary processes. Mothers allocate to the eggs diverse antioxidants that protect the embryo from oxidative stress. In the yellow-legged gull (Larus michahellis), yolk antioxidant capacity varied markedly among clutches and declined considerably with egg laying date. Analysis of bioptic yolk samples from clutches that were subsequently partially cross-fostered revealed a positive effect of yolk antioxidant capacity on embryonic development and chick growth, but not on immunity and begging behaviour, while controlling for parentage and common environment effects. Chick plasma antioxidant capacity varied according to rearing environment, after statistically partitioning out maternal influences mediated by egg quality. Thus, the results of this study indicate that egg antioxidants are important mediators of maternal effects also in wild bird populations, especially during the critical early post-hatching phase. [source] Local environment effects on exchange interactions in dilute magnetic semiconductorsPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 12 2006K. Sato Abstract We calculate effective exchange interactions in dilute magnetic semiconductors by taking local environment effects into account. The effects of local impurity configurations are considered by embedding a large cluster into the effective medium calculated by the Korringa-Kohn-Rostoker coherent potential approximation (KKR-CPA) method. Calculated exchange interactions by our cluster embedding method differ from those calculated by the Liechtenstein's method, because in our method the multiple scattering effect between site i and j is fully included. It is also found that the calculated exchange interactions strongly depend on the position of the impurities in the cluster other than site i and j. The average of the configuration dependent interactions approximately converge to the two impurity embedding results. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Inheritance of heading time in spring barley evaluated in multiple environmentsPLANT BREEDING, Issue 3 2001L. W. Gallagher Abstract The inheritance of heading time of spring barley was studied in three extremely early genotypes IB, RL and ,Mona' (M), which is homozygous recessive for the early maturity ea8 (=eak) gene conferring extreme earliness under short daylengths and is relatively photoperiod insensitive, and five (GP, MA, PS, NU and BA) spring genotypes that are early to intermediate for heading time. Frequency distributions of F2 generations grown at Ouled Gnaou, Morocco (32°15, N), an environment which maximizes differences between photoperiod-insensitive and photoperiod-sensitive genotypes, indicated that across populations many loci were segregating in a complex Mendelian manner. IB and RL were both homozygous recessive for the ea8 gene, which conferred an early heading time. RL had partially dominant alleles at second locus (Enea8), which enhanced its earliness. Recovery of only progeny within the parental range of genotypes for heading time from the crosses of RL/M and IB/M suggests that numerous loci remained suppressed, perhaps latent, given their diverse parentage. The ea8 recessive homozygote in RL suppressed another unidentified locus which, when homozygous recessive in the absence of the ea8 recessive homozygote, conferred extreme earliness in one short daylength environment (Ouled Gnaou, Morocco) but was undetected in another environment (Davis, CA, USA). Epistatic gene action and genotype × environment effects strongly influenced heading time. In addition to a genetic system consisting of single-locus recessive homozygotes conferring photoperiod insensitivity, a second genetic system, based on dominant alleles at one or a few loci, derived from the early heading Finnish landrace ,Olli', also confers extremely early heading time under short daylengths and relative photoperiod insensitivity in the genotype GP. [source] Evaluation of relative growth performance and genotype by environment effects for cross-bred yellow perch families reared in communal ponds using DNA parentage analysesAQUACULTURE RESEARCH, Issue 12 2009Han-Ping Wang Abstract From 24 mating sets, 6300 fingerling of yellow perch (Perca flavescens) were stocked into one pond and equal numbers of progeny from six representative sets out of the 24 were stocked into each of two other ponds. After communal rearing for 21 months, total length and body weight were assessed for n=300 fish in each of the three ponds and molecular pedigrees were performed for each sampled individual to assign the progeny back to the original parents. The overall average number of alleles per locus was A=16.4 and observed and expected heterozygosities were Ho=0.88 and He=0.77 respectively. The mean weight of random samples and the top 10% fast-growing fish from the pond with all the sets was significantly greater than those from either of the two replicate ponds with six crosses. For the two replicate ponds, no significant differences were found in family rankings and assignment of the top 10% fast-growing fish, indicating that families with superior growth performance in one pond also exhibited the same superior growth performance in the replicate pond. However, there were no significant correlations detected in family mean weights of the top 10% fish between any two of the three ponds. [source] | ||||||||||